I'm doing my DIY project as an FM transmitter. When finding somewhere to buy a winding inductor, I found another type of inductor called 'axial inductor'. It's very strange to me; if it's an inductor, it seems more convenient than winding an inductor. Should I buy it instead of winding my own inductor?

1 Answer
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Probably not if it's intended as the resonating coil in a 100MHz FM transmitter. Chances are this inductor will have a self-resonant-frequency below your transmission frequency and then it will behave like a capacitor. Also there are the inductor's losses to consider - basically you need a fairly high Q at your operating frequency but the small ferrite the inductor may be wound on may have high losses over (say) 500kHz.

If you are using the inductor at non-critical frequencies in non-critical areas of the circuit then maybe it'll be OK. My advice as usual on these type of questions, read the data sheet and understand that the inductor has self-resonance due to interwinding capacitance and losses that may rise exponentially with frequency.